（1）问题现象
SQL> conn hr/hr
ERROR:
ORA-00257: archiver error. Connectinternal only, until freed.
Warning: You are no longer connected toORACLE.
（2）问题分析
在oracle 10g后，若flashback开启，后台归档程序进行(ARCn)将会自动在闪回恢复区中创建每个归档重做日志的一个副本，而flashback区域有大小限制：
SQL> show parameter recovery
NAME TYPE VALUE
----------------------------------------------- ------------------------------
db_recovery_file_dest string /opt/oracle/flash_recovery_area
db_recovery_file_dest_size big integer 3882M
recovery_parallelism integer 0
当falshback空间已满，则连接数据库失败。
（3）问题解决
l 删除部分归档日志
l 增加falshback的空间限制
SQL> alter system set DB_RECOVERY_FILE_DEST_SIZE=20g;
System altered.
（4）监控flashback
l 查看闪回恢复区的相关信息
SQL> select * from v$recovery_file_dest;
NAME SPACE_LIMITSPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES
--------------------------------------------------- ---------- ----------------- ---------------
/opt/oracle/flash_recovery_area 2.1475E+10 4190778368 0 95
l 查看flash area的使用率
SQL> select * from v$flash_recovery_area_usage;
FILE_TYPE PERCENT_SPACE_USEDPERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES
-------------------- ------------------------------------------- ---------------
CONTROL FILE 0 0 0
REDO LOG 0 0 0
ARCHIVED LOG 19.51 0 95
BACKUP PIECE 0 0 0
IMAGE COPY 0 0 0
FLASHBACK LOG 0 0 0
FOREIGN ARCHIVED LOG 0 0 0
7 rows selected.
其它内容请参考
oracle之Flash Recovery Area全面介绍
http://blog.csdn.net/jediael_lu/article/details/8854477